Identification and characterization of α-xylosidase involved in xyloglucan degradation in Aspergillus oryzae
Identification and characterization of α-xylosidase involved in xyloglucan degradation in Aspergillus oryzae
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DOI：
10.1007/s00253-019-10244-z
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发表时间：
2019-11-28
影响因子：
5
通讯作者：
Yaoi, Katsuro
中科院分区：
文献类型：
--
作者：
Matsuzawa, Tomohiko;Kameyama, Akihiko;Yaoi, Katsuro
米曲霉产生参与木葡聚糖降解的水解酶，并在木葡聚糖寡糖存在的情况下诱导编码木葡聚糖寡糖水解酶的基因的表达。编码 α-木糖苷酶（称为 AxyA）的基因在木葡聚糖寡糖存在下被诱导，在巴斯德毕赤酵母中被鉴定和表达。 AxyA 是糖苷水解酶家族 31 (GH31) 的成员。 AxyA 将异报春糖（α-d-吡喃木糖基-(1 -> 6)-d-吡喃葡萄糖）水解为 d-木糖和 d-葡萄糖，并与其他木葡聚糖寡糖如 XXXG（七糖、Glc(4)Xyl(3)）和 XLLG（九糖、 Glc(4)Xyl(3)Gal(2))。与其他木葡聚糖寡糖相比，异报春糖是优选的 AxyA 底物。在 XXXG 的水解过程中，AxyA 从一分子 XXXG 中释放出一分子 d-木糖，生成 GXXG（六糖，Glc(4)Xyl(2)）。 AxyA 不包含分泌信号肽并保留在细胞内。 AxyA 的细胞内定位可能有助于确定水解酶作用于木葡聚糖寡糖的顺序。
Aspergillus oryzae produces hydrolases involved in xyloglucan degradation and induces the expression of genes encoding xyloglucan oligosaccharide hydrolases in the presence of xyloglucan oligosaccharides. A gene encoding alpha-xylosidase (termed AxyA), which is induced in the presence of xyloglucan oligosaccharides, is identified and expressed in Pichia pastoris. AxyA is a member of the glycoside hydrolase family 31 (GH31). AxyA hydrolyzes isoprimeverose (alpha-d-xylopyranosyl-(1 -> 6)-d-glucopyranose) into d-xylose and d-glucose and shows hydrolytic activity with other xyloglucan oligosaccharides such as XXXG (heptasaccharide, Glc(4)Xyl(3)) and XLLG (nonasaccharide, Glc(4)Xyl(3)Gal(2)). Isoprimeverose is a preferred AxyA substrate over other xyloglucan oligosaccharides. In the hydrolysis of XXXG, AxyA releases one molecule of d-xylose from one molecule of XXXG to yield GXXG (hexasaccharide, Glc(4)Xyl(2)). AxyA does not contain a signal peptide for secretion and remains within the cell. The intracellular localization of AxyA may help determine the order of hydrolases acting on xyloglucan oligosaccharides.